Exploring virulence factors of Helicobacter pylori isolated from gastric biopsy.

BACKGROUND: Helicobacter pylori (H. pylori) colonizes human gastric mucosa and is classified as class one carcinogenic bacteria. In this regard, this study aimed to detect major virulence factors in H. pylori strains recovered from gastric biopsy in patients referred to Aras Clinique in Ardabil, northwest of Iran (2019-2021). MATERIALS AND METHODS: In this descriptive-cross sectional study, 287 dyspeptic patients were included. For bacterial isolation, gastric biopsy specimens (n=287) were taken from gastric antrum, then aseptically were cultured on the selective medium and incubated at 37C in microaerophilic conditions for 3-5 days. RESULTS: 25.18% of all (n = 70) patients were found to be infected with H. pylori upon endoscopy. Of them, 9 patients (12.857%) and 2 patients (2.875%) had peptic ulcer disease and gastric cancer respectively. According to the different patterns of virulence factors, 57 virutypes were identified in which oipA-vacAs1-vacAm2 (3, 4.28% n =) and oipA-vacAs1-vacAs2-vacAm2 (3, 4.28% n =) were the most common patterns. The simultaneous presence of vacAS2, vacAm2 and hopQ2 genes was observed in both patients with gastric cancer. OipA (n = 562.5%), VacAs1 (n = 6.75%), VacAs2 (n = 6.75%), and VacAm2 (n = 787.5%) were found to be the most prevalent virulence factor. CONCLUSION: According previous studies, it is confirmed that the cagPAI gene cluster and vacA gene alleles are strongly correlated with gastritis and gastrointestinal tract adenocarcinomas. Our study indicated that 50% of the indigenous strains of H. pylori harbor these oncogenic genes and they are hypervirulent.

Molecular identification of multiple drug resistance (MDR) strain of Mycobacterium tuberculosis.

BACKGROUND AND OBJECTIVES: Isoniazid and rifampin are the first -line drugs against Mycobacterium tuberculosis. Resistance to these important drugs is a serious threat to human public health. Therefore, this study aimed at molecular detection of resistance to these valuable drugs. MATERIALS AND METHODS: In this descriptive cross-sectional study, 111 non - duplicated clinical samples including sputum and Bronchoalveolar lavage (BAL) samples were collected from patients referred to the Ardabil Health Center between 2017 and 2020. The samples were first examined by microscopic method, then their DNA was extracted using the boiling method. Specific primers and MAS-PCR method were employed for the detection resistance to isoniazid and rifampin drugs and identification of MDR strain. RESULTS: of 111 specimens, 15.3% belonged to NTM. In total, the resistance rate to isoniazid and rifampin was 17% and 27% respectively while the resistance rate to isoniazid and rifampin among NTM was 61.54% and 38.46%. CONCLUSION: In our study, the prevalence of resistance to isoniazid and rifampin among Mycobacterium tuberculosis complex(MTC) and non-tuberculous mycobacteria(NTM) was investigated using the MAS-PCR method. This work highlighted the high anti- tuberculosis resistance rate among NTM compared to MTC strains.

Improvement the expression and purification of Loa22: a lipoprotein with OmpA domain from pathogenic Leptospira serovars.

Background and Objectives: One of the highly conserved outer membrane proteins expressed only by pathogenic Leptospires is Loa22. The study aims is to achieve the optimum conditions for high expression of recombinant Loa22 (rLoa22) protein. Materials and Methods: Complete coding sequence of loa22 gene sub-cloned into a pET32a (+) expression vector. BL21 competent E. coli (pLysS) used as expression host for transformation. The recombinant clones selected on ampicillin plates and subjected to PCR by using pET T7 primers. Then expression conditions optimized by adjusting parameters such as culture media, induction time, temperature, and IPTG concentration. Results: SDS-PAGE analysis showed that high production of rLoa22 protein obtained when post induction incubation, IPTG concentration, and duration of induction were 37°C, 0.1 M and 5 h in 2×TY medium respectively. The purification of rLoa22 protein under native conditions using Ni-NTA pull-down was optimum in one hour binding at 37°C, five times washing process and elution buffer with a pH 7.4 and a 0.3 M imidazole concentration. Conclusion: The findings of the study led to high production of pure Loa22 protein, which can form the basis for future investigation on the design of rapid diagnostic tests and more effective vaccine candidates for leptospirosis.

Designing of novel chimeric PvpA-pMGA protein of Mycoplasma gallisepticum, applicable for indirect ELISA.

BACKGROUND: Mycoplasma gallisepticum is the primary agent of chronic respiratory disease in chickens creating important economic losses in poultry industry. pMGA and pvpA genes encode major surface proteins in M. gallisepticum containing pathogenic, antigenic, and immune evasion characteristics. The objective of the present study was to design, express, and purify the recombinant chimeric PvpA-pMGA protein from M.gallisepticum for using in serological diagnostic test. METHODS: Antigenic regions of PvpA and pMGA proteins were predicted for designing chimeric pvpA-pMGA gene construct. The codon optimized sequence was cloned into the expression vector pET32a+ and transformed into the Escherichia coli strain BL21 (DE3). The pET32a-PvpA-pMGA recombinant plasmid was expressed and confirmed by SDS-PAGE and immunoblotting. PvpA-pMGA recombinant protein (20µg and 50µg), ts-11 vaccine strain, and S6 strain that formulated by montanide adjuvant and two control groups (PBS and adjuvant) were injected subcutaneously to six groups of chickens. RESULTS: High yield of protein was purified amount 138 mg/L by affinity batch formation method. Indirect ELISA showed the levels of antibodies in rPvpA-pMGA was significantly higher than ts-11 and S6 groups (p<0.05). The results indicated that antigen-specific response was successfully elicited by the rpMGA-PvpA in chickens. The result of the ELISA with sera collected from ts-11 and S6 groups showed that indirect PvpA-pMGA-ELISA is appropriate candidate for detection of specific antibodies against M. gallisepticum with 100% sensitivity and specificity. CONCLUSIONS: The rPvpA-pMGA is a highly candidate immunogenic protein which induced high amount of humoral immune response. Novel rPvpA-pMGA protein could be useful for evaluation of antibody level in vaccinated poultry flocks.

Highly Expression and Purification of an Antigenic Region (D259-R462) of Adenylate Guanylate Cyclase Protein, Applicable for ELISA Test

Abstract Leptospirosis is a wide spread bacterial zoonosis that is common worldwide. The disease symptoms are mild or acute. Leptospira has pathogenic and non-pathogenic species; it has a lot of surface antigens. Adenylate Guanylate Cyclase (AGC) is a membrane protein that is found only in pathogenic species. In this study, the complete coding sequences of AGC protein of 242 pathogen serovars were investigated by bioinformatics tools. A Pattern was selected as a target sequence based on high prevalence pathogenic serovars in Iran Antigen sites; moreover, B-cell and T-cell epitopes were predicted by IEDB web server. An antigen site amino acid (D259-R462) in complete coding sequence of AGC protein was selected. This nucleotide related sequence was cloned into the pET32a+ expression vector. Expression of recombinant protein was optimized in E. coli strain Bl21-DE3 by 0.2mM IPTG after 16-hour incubation at 37 ͦ C and confirmed by 10% SDS-PAGE and western blotting. Antigenic peptide D259-R462 was highly expressed as Trx tag fusion protein. Recombinant peptide (rAcB) was purified by 6M urea from inclusion body with high extent yield 514.2 mg per 1000ml culture of E. coli. 20µg rAcB protein with montanide adjuvant was injected subcutaneously in BALB/c mice. Results showed that the recombinant peptide D259-R462 was produced significant antibody compared to adjuvant and PBS groups. The induced antibody in sera of immunized animal with Leptospira vaccine was detected by 250 ng of rAcB coated in ELISA microplate. This study demonstrated that antigenic region (D259-R462) of AGC protein might be useful for evaluation of antibody level in vaccinated animal.

Investigation of iron uptake and virulence gene factors (fur, tonB, exbD, exbB, hgbA, hgbB1, hgbB2 and tbpA) among isolates of Pasteurella multocida from Iran.

BACKGROUND AND OBJECTIVES: Iron is an essential compound in metabolic pathway of wide range of organisms. Because of limited free iron supply in mammalian and avian hosts, bacteria have applied various ways to acquire iron. MATERIALS AND METHODS: In this study, the frequency of 8 iron acquisition factors was examined among 63 avian and ovine Pasteurella multocida field isolates and their vaccine strains using PCR method. RESULTS: Five candidate genes (fur, tonB, exbD, exbB and hgbA) were identified among all isolates. For the first time, 2 loci (hgbB1 and hgbB2) of the hgbB gene were identified, which were previously reported as 1 gene. Also, it was found that 5 ovine and 1 avian isolates possessed all the virulence factors, which could also be considered for evaluating the frequency of other virulence factors. CONCLUSION: More studies need to be conducted on the frequency of all other virulence factors among these isolates, which can provide basic information for improvement or substitution of current vaccinal strains. Overall, as the new designed sets of primers showed more potential in detecting the corresponded genes, researchers can consider them in further studies.

Analysis of natural recombination and host-related evolutionary dynamics of avian avulavirus 1 isolates based on positive and negative selection from 1948 to 2017.

Adaptation and evolution of avian avulavirus 1, or Newcastle disease virus (NDV), has led to tremendous economic losses worldwide. The occurrence of natural recombination and selection pressure has been traced for NDV based on a few recent reports, but a dominant pattern based on genomic characteristics is lacking. Here, we used bioinformatics tools to search for evidence of recombination in all of the available complete genome sequence of NDV (462 sequences) using RDP4 software. Geographical linkage and host cell relationships of recombinant viruses were also investigated, and a study of the adaptive evolution of avian avulavirus 1 was performed. The results revealed that recombination events could occur in any gene fragment of the NDV genome. Moreover, class I NDV isolates from wild birds could associate to generate a putative recombinant virus with a class II genome backbone. In addition, not only avirulent-virulent hybrid genotypes but also virulent-virulent natural recombinant NDV viruses were generated. Investigation of geographic relationships of recombinant isolates indicated that the highest rate of recombination occurs in Asia and the Middle East, which can be influenced by vaccination failure, evasion of the immune response, live-bird markets, and the bird trade. The M and NP genes were found to have higher negative selection rates than the other genes, which might lead to the deletion of inadaptable sequences and result in more conserved sequences. Based on our analysis, the highest rate of positive selection was observed in the L, F and HN genes, which we suggest could lead to the occurrence of evolved viruses with high pathogenicity and a better chance of survival under extreme conditions.

Molecular characterization of quinolone resistant Shigella spp. isolates from patients in Ardabil, Iran.

BACKGROUND AND OBJECTIVES: Shigella is an etiological agent of shigellosis. Antibiotic therapy has a critical role in decreasing serious complications of shigellosis. The present study aimed to determine the multi-drug resistance strains and to detect fluoroquinolone related mutations. MATERIALS AND METHODS: In this descriptive, cross sectional study, a total of 113 Shigella isolates were collected from 1280 patients admitted to Bu-Ali hospital in Ardabil province during 2015-17. Antibiotic resistance pattern of isolates was evaluated using Kirby Bauer method and finally, the MICs of ciprofloxacin were determined. In order to determine any mutations in QRDR region, parC and gyrA genes of resistant strains were amplified and sequenced. RESULTS: Shigella spp. isolates were identified using ipaH amplification and rfc and wbgz genes were used for molecular detection of S. flexneri and S. soneii, respectively. Our results showed that the predominant species in Ardabil province was S. sonnei (69.91%). Most of isolates (82%) were resistant to trimethoprim/sulfamethoxazole (TMP/SMX); 51% were nalidixic acid resistant and 4.4% were floroquinolones resistant. All examined isolates were susceptible to imipenem (100%). Mutation in gyrA and parC genes were detected in all fluoroquinolone resistant isolates (5 isolates). Although, in this study the rate of resistance to ciprofloxacin was low, but in the lack of preventive strategy it will be a major challenge of public health in future. CONCLUSION: This study provided information on the prevalence and antimicrobial susceptibility patterns of Shigella isolates in Ardabil province, Iran. Also this study showed a high-level of resistance to commonly used antibiotics among Shigella isolates.

Designing a Novel Recombinant HN Protein with Multi Neutralizing Antigenic Sites and Auto Tag Removal Ability Based on NDV-VIIj for Diagnosis and Vaccination Application.

Hemagglutinin-neuraminidase (HN) protein besides its mediation in viral pathogenesis, is composed of various antigenic sites which stimulate production of host's antibodies. Thus, application of this protein in serological tests and vaccination plays a major role in biosecurity and control programs. In the present study, we designed a recombinant HN protein containing different neutralizing antigenic sites with velogenic patterns, and sub-cloned it into pET-43.1a+ expression vector. The expression of NusA-HN recombinant protein was induced. Affinity chromatography protein purification using HisPur™ Ni-NTA was then conducted. Moreover, we performed western-blot technique using HRP-conjugated Anti His-Tag. Results revealed that following induction of recombinant protein, two distinct bands of HN-61 kDa and NusA-63 kDa were purified and identified by western-blotting. We recommend further analysis should be carried out to determine the functional role of this recombinant protein in enzyme-linked immunosorbent assays for Newcastle disease diagnosis. This HN protein containing multi neutralizing antigenic sites might also be applicable in vaccination programs to increase vaccines potency.

Expression of G1- epitope of bovine ephemeral fever virus in E. coli : A novel candidate to develop ELISA kit.

Bovine ephemeral fever is an acute and arthropod-borne viral disease of cattle and water buffalo which occurs seasonally in most of the world tropical and subtropical regions. The epizootic feature of the disease has been reported in Iran with serious economic consequences. The surface glycoprotein G of bovine ephemeral fever virus (BEFV) is composed of 4 antigenic sites (G1-G4) and plays the main role for eliciting neutralizing antibodies and protective immunity. The G1 - epitope is a linear antigenic site and conserved among BEFV strains. In order to develop an ELISA test based on G1-epitope as coating antigen, this study was carried out to express the recombinant G1-epitope of BEFV in prokaryotic system. Using PCR and specific primers, a length of 88 amino acid of the G glycoprotein of BEFV including G1- epitope was amplified and cloned into the expression vector pGEX-4T-1, with the GST moiety. The recombinant plasmid (pGEX-4T-1-G1) was then transformed into Escherichia coli BL21 and expression of fusion protein was induced by 0.10 mM IPTG. The maximum expression of the fusion protein was obtained at 16 hr post induction as verified by SDS-PAGE electrophoresis, and it was also confirmed that this protein bearing G1- epitope is sufficiently biologically active to bind to anti-BEFV serum in western blot experiment.

Molecular evolution and epidemiological links study of Newcastle disease virus isolates from 1995 to 2016 in Iran.

In the case of Newcastle disease virus, multiple factors such as host adaptation, immune response evasion, and selective pressures have been suggested to result in evolution of viruses and the emergence of genetic variants. Multiple studies on virus classification and global epidemiological links have yielded consistent data. Here, we have performed a molecular analysis study of circulating Newcastle disease viruses in Iran (1995-2016). According to evolutionary divergences, subgenotype VIg, VIj, VIIj, VIId, XIIIa and XIIId isolates have been circulating in the country during a 21-year period. Based on data analysis, VIg isolates shared highest sequence identity with Russian and Polish isolates of the VIg subgenotype, while VIj subgenotype isolates (2012) were most similar to a virus isolated in 2015 in India. Analysis of the evolutionary divergence of subgenotype VIIj suggests that Chinese and Ukrainian viruses may have played a crucial role in the emergence of VIIj isolates. Evolutionary difference studies also indicated that XIIIa isolates circulating in Iran may have caused the emergence of adapted variants of subgenotype XIIId. Therefore, we propose that the evolutionary and epidemiological study of virulent Newcastle disease viruses could help to provide accurate molecular data about variants circulating in the region, thus aiding in the design of more efficient recombinant vaccines.

A Novel PCR Assay for Detecting Brucella abortus and Brucella melitensis.

OBJECTIVES: Brucellosis is a major zoonotic disease that poses a significant public health threat worldwide. The classical bacteriological detection process used to identify Brucella spp. is difficult and time-consuming. This study aimed to develop a novel molecular assay for detecting brucellosis. METHODS: All complete sequences of chromosome 1 with 2.1-Mbp lengths were compared among all available Brucella sequences. A unique repeat sequence (URS) locus on chromosome 1 could differentiate Brucella abortus from Brucella melitensis. A primer set was designed to flank the unique locus. A total of 136 lymph nodes and blood samples were evaluated and classified by the URS-polymerase chain reaction (PCR) method in 2013-2014. RESULTS: Biochemical tests and bacteriophage typing as the golden standard indicated that all Brucella spp. isolates were B. melitensis biovar 1 and B. abortus biovar 3. The PCR results were the same as the bacteriological method for detecting Brucella spp. The sensitivity and specificity of the URS-PCR method make it suitable for detecting B. abortus and B. melitensis. CONCLUSION: Quick detection of B. abortus and B. melitensis can provide the most effective strategies for control of these bacteria. The advantage of this method over other presented methods is that both B. abortus and B. melitensis are detectable in a single test tube. Furthermore, this method covered 100% of all B. melitensis and B. abortus biotypes. The development of this URS-PCR method is the first step toward the development of a novel kit for the molecular identification of B. abortus and B. melitensis.

Identification of novel Newcastle disease virus sub-genotype VII-(j) based on the fusion protein.

Newcastle disease virus (NDV) is believed to be the cause of fatal poultry disease worldwide. The fusion (F) protein plays a key role in virus pathogenesis, and it is also used for Newcastle disease virus classification. In this study, we determined the complete coding sequence of the F gene in new velogenic NDV isolates with an intravenous pathogenicity index (IVPI) of 1.8 and a mean death time (MDT) of 72 or 48 h. Complete sequences of the F genes of new Iranian isolates were amplified and sequenced in both directions. These isolates were compared to 195 nucleotide sequences from GenBank (available as of 07/17/2016). A phylogenetic tree was constructed for the F gene, using MEGA6 software with statistical analysis based on 500 bootstrap replicates. Evolutionary distances revealed that the new virulent isolates from Iran belonged to genotype VII in a new distinct sub-genotype named VII-(j). This new sub-genotype showed 3% divergence from genotype VIId. Recombination analysis showed that these new isolates were not recombinant NDVs.

Construction of a DNA Vaccine Encoding Mtb32C and HBHA Genes of Mycobacterium tuberculosis.

BACKGROUND: Tuberculosis (TB) is a contagious disease caused by Mycobacterium tuberculosis. Development of a new vaccine for tuberculosis requires immunogenic antigens capable of inducing suitable and long-lasting T cell immunity. The emergence of multidrugs and extensively drug-resistant strains of M. tuberculosis has made it a global public health concern. OBJECTIVES: DNA vaccine is a straightforward method to introduce antigens to the host. In the present study, two immunodominant mycobacterial antigens (Mtb32C and HBHA) were isolated and cloned into pcDNA3.1 (+) to design and construct a new DNA vaccine. This vector is capable of producing new potent chimeric protein. MATERIALS AND METHODS: Mtb32C (Rv0125) and heparin-binding haemagglutinin adhesion (HBHA) genes were amplified using polymerase chain reaction (PCR) of M. tuberculosis H37Rv genome and ligated into pcDNA3.1 (+). Colony-PCR and restriction enzyme analysis were used to confirm the accuracy of the cloning procedure. RESULTS: In the current study, recombinant pcDNA3.1 (+) vector containing Mtb32C and HBHA genes was successfully constructed. The desired size of DNA fragment was observed using single and double digestion methods. CONCLUSIONS: Mtb32C and HBHA genes were successfully isolated from H37Rv genome and cloned into an eukaryotic expression vector. This vector can be considered as a vaccine to evaluate immune responses in animal models.

Genetic characterization of the wboA gene from the predominant biovars of Brucella isolates in Iran.

INTRODUCTION: Brucella spp. are gram-negative, facultative intracellular bacteria pathogens responsible for brucellosis, a zoonotic disease that can cause abortion, fetal death, and genital infections in animals and undulant fever in humans. Lipopolysaccharide (LPS) is known as a major virulence factor of Brucella spp. The wboA gene is capable of encoding a glycosyltransferase that appears to play a major role in LPS biosynthesis. Hence, the characterization of this gene can help in the clarification of the pathogenicity of Brucella spp. METHODS: This study was carried out at Razi Vaccine and Serum Research Institute in 2011. Briefly, the wboA gene in B. abortus biovar 3 and B. melitensis biovar 1, the predominant biovars in Iran, were amplified by using two pairs of specific primers. Polymerase chain reaction (PCR) products were cloned into a thymine-adenine (TA) cloning vector and transformed into an E. coli DH5α before being sequenced. Multiple alignments of identified sequences were performed, with all wboA sequences deposited in the GenBank sequence database. RESULTS: This study showed that a mismatch has occurred in B. melitensis biovar 1; this biovar is predominant in Iran. In contrast, the wboA gene from B. abortus biovar 3 was similar to that of other B. abortus variations. CONCLUSION: The comparison and alignment of the wboA gene of native Brucella strains in Iran to all wboA sequences deposited in GenBank revealed that the wboA gene has changed in the long term; hence, because of its unique nucleotide pattern, the gene can be used for specific diagnosis of B. abortus and B. canis.

Identification of Six Introns in a Partial Sequence of Echinococcus granulosus Paramyosin Gene.

OBJECTIVE: Paramyosin is a major protein produced by the metacestode cyst of Echinococcus granulosus, the causative agent of cystic hydatid disease. This protein has been shown to play an important role in modulating host immune responses. In this study, we attempted to characterize the noncoding sequence of the paramyosin gene. METHODS: Genomic DNA was isolated from G1 Iranian hydatid cysts. A DNA fragment of 3200 bp in length was amplified from the paramyosin gene. The polymerase chain reaction (PCR) product was cloned to the pTZ57T vector and sequenced by M13 primers and then compared with unique cDNA coding sequences of E. granulosus (Z21787) and Taenia solium (AY034087). RESULTS: Six introns I (107 bp), II (75 bp), III (47 bp), IV (921 bp), V (19 bp), and VI (456 bp) were identified in the partial sequence of the paramyosin gene. Some nucleotide changes were observed in three exons I, IV, and VI. CONCLUSION: This data could help scientists in better understanding the possible alternative splicing and designing a real-time PCR technique for the evaluation of the transcription levels of paramyosin in the stages of the Echinococcus sp. life cycle.

Molecular Study of the G1 Haplotypes of Echinococcus granulosus from Iran Based on Cytochrome C Oxidase (Subunit 1) Sequence.

OBJECTIVE: In this study, we attempted to identify new Echinococcus granulosus isolates in the North West provinces of Iran based on the mitochondrial cytochrome c oxidase subunit 1 (CO1) sequence. METHODS: Twenty-nine hydatid cysts from sheep and goats were collected. Genomic DNAs were extracted, and a partial sequence of the CO1 gene was amplified. Polymerase chain reaction products were cloned and sequenced with M13 primers in both directions. RESULTS: All Iranian isolates were located in G1 and G3 genotypes. For the first time, a new G1 haplotype in two Iranian isolates were identified. CONCLUSION: It seems that this new haplotype was transmitted from Jordan to Iran or vice versa.

Phylogenetic study on the 5'-untranslated region of bovine viral diarrhoea virus isolates from Iran.

Bovine viral diarrhoea virus is a pathogen of bovids associated with reproduction system, causing in infected animals a range of ailments, from abortion to congenital defects. In this article, the nucleotide structure of the 5'-untranslated region (5-UTR) from 7 Iranian bovine diarrhoea virus (BVDV) isolates was characterized and subjected to comparative analysis against a panel of BVDV isolates from different sources. To this end, a 288 bp-long stretch of the internal ribosome entry site was amplified by RT-PCR. The PCR products subsequently cloned into PTZ57T vector and sequenced using T7 promoter primers. This resulted in detection of 3 new point mutations G → A and G → T in 2 isolates. When these findings were phylogenetically assessed, all the examined Iranian isolates were deemed to belong to the type1 of BVDV. Besides, 2 subtypes were identified among these isolates. In group A, a high level of similarity (99.2%) between Iranian isolates with a cytopathic Australian strain of BVDV-1c was detected; while in group B, the 4 Iranian isolates proved to be very similar to NADL-like BVDV-1a strains. We believe that the surprisingly high level of similarity between group A Iranian isolates and their corresponding Australian strain is likely to be an indication of a shared common ancestor. If correct, the most likely explanation of this observation is the introduction of such strains from Australia to Iran, possibly through exportation of infected live animals or animal productions (e.g. semen and meat) at some points in the past. Nevertheless, this hypothesis remains to be proved as further epidemiological work at genomic level is required to understand population of BVDV in Iran.

Molecular identification of the ompL1 gene within Leptospira interrogans standard serovars.

INTRODUCTION: Leptospirosis, caused by infection with pathogenic Leptospira species, is one of the most prevalent zoonotic diseases in the world. Current leptospiral vaccines are mainly multivalent dead whole-cell mixtures made of several local dominant serovars. Therefore, design and construction of an efficient recombinant vaccine for leptospirosis control is very important. OmpL1 is an immunogenic porin protein that could be of special significance in vaccination and serodiagnosis for leptospirosis. METHODOLOGY: Three strains belonging to pathogenic L. interrogans were analyzed. The specific primers for proliferation of the ompL1 gene were designed. The amplified gene was cloned. In order to investigate the ompL1 nucleotide sequence and homological analysis of this gene, ompL1 genes cloned from standard vaccinal Leptospira serovars prevalent in Iran were sequenced and cloned. RESULTS: PCR amplification of the ompL1 gene using the designed primers resulted in a 963 bp ompL1 gene product. The PCR based on the ompL1 gene detected all pathogenic reference serovars of Leptospira spp. tested. Based on alignment and phylogenetic analysis, although the ompL1 nucleotide sequence was slightly different within three vaccinal serovars (100%-85% identity), amino acid alignment of the OmpL1 proteins revealed that there would be inconsiderable difference among them. CONCLUSION: The ompL1 gene of the three isolates was well conserved, differing only by a total of 6 bp and the proteins by 2 amino acids. The cloned gene could be further used for expression and recombinant OmpL1 as an efficient and conserved antigen, and may be a useful vaccine candidate against leptospirosis in our region.

Induction of protective T-helper 1 immune responses against Echinococcus granulosus in mice by a multi-T-cell epitope antigen based on five proteins.

In this study, we designed an experiment to predict a potential immunodominant T-cell epitope and evaluate the protectivity of this antigen in immunised mice. The T-cell epitopes of the candidate proteins (EgGST, EgA31, Eg95, EgTrp and P14-3-3) were detected using available web-based databases. The synthesised DNA was subcloned into the pET41a+ vector and expressed in Escherichia coli as a fusion to glutathione-S-transferase protein (GST). The resulting chimeric protein was then purified by affinity chromatography. Twenty female C57BL/6 mice were immunised with the antigen emulsified in Freund's adjuvant. Mouse splenocytes were then cultured in Dulbecco's Modified Eagle's Medium in the presence of the antigen. The production of interferon-γ was significantly higher in the immunised mice than in the control mice (> 1,300 pg/mL), but interleukin (IL)-10 and IL-4 production was not statistically different between the two groups. In a challenge study in which mice were infected with 500 live protoscolices, a high protectivity level (99.6%) was demonstrated in immunised BALB/C mice compared to the findings in the control groups [GST and adjuvant (Adj)]. These results demonstrate the successful application of the predicted T-cell epitope in designing a vaccine against Echinococcus granulosus in a mouse model.